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Search: id:A133357
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| A133357 |
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Number of 2-colorings of a 3 X n rectangle for which no subsquare has monochromatic corners. |
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+0
1
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OFFSET
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1,1
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COMMENT
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Figures obtained via clever exhaustion, using Gray Codes.
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REFERENCES
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J. Solymosi, "A Note on a Question of Erdos and Graham", Combinatorics, Probability and Computing, Volume 13, Issue 2 (March 2004) 263 - 267.
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LINKS
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Sci.math, Discussion of a related problems
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EXAMPLE
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a(1) = 8, because there are no conditions.
a(2) = 50 because if the middle row is not monochromatic, the top and bottom rows are unconstrained, contributing 2*4*4. if the middle row is monochromatic, the top and bottom rows can each take on only 3 values contributing 2*3*3.
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CROSSREFS
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Cf. A133129.
Sequence in context: A133426 A033463 A030279 this_sequence A081675 A081180 A052177
Adjacent sequences: A133354 A133355 A133356 this_sequence A133358 A133359 A133360
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KEYWORD
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nonn
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AUTHOR
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Victor S. Miller (victorsmiller(AT)gmail.com), Dec 21 2007
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